Holder's investigation

Some people, the president and the 08 Republican nominee for president included, keep asserting that with respect to allegations of torture during the Bush administration, we should "look forward, not back". And Holder's announcement that he intended to investigate regardless generated concerns that such an investigation could hurt morale and effectiveness of the CIA.

It's hard for me to understand how these constitute effective arguments. The first suggestion is just utterly silly. First, it seems that it could be applied to any criminal investigation, all crimes have occurred in the past and yet we go back to investigate them. But it's much more dangerous in this particular case, the question of whether or not the US endorsed and/or participated in torture and whether or not the country is willing to take a stand and indicate whether or not that was permissible goes to the very heart of what the country's principles are. How can the country "move forward" while those questions remain unaddressed?

As to the CIA morale argument, well, of course, criminal investigations hurt morale at any organizations, but surely if this is a legitimate argument, then we've effectively given the CIA carte blanche. Prosecution for any criminal wrongdoing will require investigation. Any investigation will hurt morale at the CIA, so if the general principle is "Never hurt morale at the CIA", it follows that we can never prosecute any criminal wrongdoing at the CIA, so the CIA is free to do whatever they'd like.